def Pow(a,n,mod):
	s = 1
	while n:
		if n&1:	s = s*a%mod
		a = a*a%mod
		n>>=1
	return s

def IsPrime(num):
	l = [2,3,5,7,11]
	if num in l: return True
	else:
		for x in l:
			if Pow(x,num-1,num)!=1: return False
		return True

if __name__=="__main__":
	while True:
		#num,n = (int(x) for x in raw_input().split())
		#print Pow(num,n-1,n)
		#print Pow(num,n,100000000)
		#n = int(raw_input())
		#if IsPrime(n):	print n,"is prime nunber!"
		#else:	print n,"isn't prime number!"
		a,b = (int(x) for x in raw_input().split())
		#cnt = sum(1 for x in xrange(a,b) if IsPrime(x))
		cnt = 0;
		for x in xrange(a,b):
			if IsPrime(x): cnt +=1
		print "range[%d,%d): %d prime numbers" %(a,b,cnt)
